The presently disclosed and/or claimed inventive concept(s) relates generally to a liquid purification apparatus. The presently disclosed and/or claimed inventive concept(s) also relates to a method for purifying a volume of liquid with such an apparatus, as well as a beverage dispenser comprising it. The presently disclosed and/or claimed inventive concept(s) also relates to an irradiation device as such.
One of the most essential tasks in purifying water for drinking is disinfection, so as to ensure that any pathogenic microorganisms (e.g. bacteria, viruses, and/or protozoans) present in the water cannot cause illness in anyone who drinks it. It is known to perform this disinfection by the process of ultraviolet (UV) irradiation, where a volume of water being treated is bombarded with high-energy UV radiation. The UV radiation damages the DNA and RNA of the pathogenic microorganisms, destroying their ability to reproduce and effectively neutralizing their ability to cause disease.
Since such systems utilize light to disinfect, their effectiveness is reduced on liquid which is not naturally clear or which has not been filtered to remove suspended solids. The scope of “purification,” for the purposes of this document, should thus be understood as encompassing the disinfection of liquid in which turbidity is minimal.
Traditional UV liquid purification systems have employed gas-discharge lamps as UV sources, in particular mercury-vapor lamps. Recently, it has become more and more common to employ ultraviolet light-emitting diodes (UV-LEDs) as a source of ultraviolet light for irradiation. UV-LEDs have numerous advantageous aspects which makes them appealing for use in an ultraviolet liquid purification system, notably their compact size, robustness, and lack of toxic components such as the mercury vapor found in conventional lamps. The solid-state nature of UV-LEDs also enables them to be switched on and off instantly, a further advantage relative to conventional gas-discharge lamps.
There are several examples in the prior art of UV-LEDs being employed to purify a liquid by ultraviolet irradiation. For example, the document CN 202175579 describes an irradiation device in which a single tube is spiraled around an array of UV-LEDs, and the document KR 20110007554 describes a faucet with a built-in UV-LED sterilizer for treating the liquid issuing from it. In addition, the document KR 20040073732 describes a system for purifying water that is drawn from a reservoir and conducted through a sterilizer directly to a nozzle for dispensing.
However, the liquid purification systems known in the art are disadvantageous in several ways. Unlike chemical water purification means such as chlorine or ozone, ultraviolet sterilization does not have any persistent effect; liquid which has been sterilized is thus more susceptible to being re-contaminated. In the purification systems known in the art, there is a section of plumbing, generally located between the ultraviolet irradiator to an outlet of the apparatus, where water is not circulated except during the dispensing of liquid from the machine. This segment of dead space within the system gives space where pathogenic microorganisms may potentially flourish without being exposed to ultraviolet irradiation.
In the systems known in the art, this problem is solved by disposing a second irradiation device in or near the outlet itself. The liquid flowing from the spout is thus effectively irradiated twice: once by a full-power irradiation device within the machine, and once by another full-power irradiation device disposed within the spout. Since each of the irradiation devices must be sufficiently powerful to properly disinfect the liquid by itself, the cost of the apparatus and the energy required for its operation are increased. Furthermore, since the second irradiation device is disposed within the spout it is in close proximity to the opening through which the liquid is dispensed, requiring extra care and expense in providing protection to the user from exposure to the ultraviolet light generated during the dispensing of the purified liquid.
The presently disclosed and/or claimed inventive concept(s) seeks to provide a system for purifying a liquid by ultraviolet germicidal irradiation with an improved effectiveness and reduced energy consumption relative to those known in the art.